Bird stop: In addition to preventing birds from nesting in the hollows of the tile, this length of formed metal or foam elevates the first course of tile so that it is positioned at the same angle as subsequent courses.

Blisters: Bubbles that may appear on the surface of asphalt roofing after installation.

Box scuppers:  Scuppers used on the outside edge of a roof with no overhang

Built-in Gutters: a gutter on the roof deck with a higher fascia board creating a trough to collect water.

Built-up roof: An outer covering of a comparatively flat roof, consisting of 3 layers of saturated felt and 3 layers of tar. As laid, each layer is mopped with hot tar or asphalt. The top layer is finished with a mineral or rock covering and a special coating.

Bundle: A package of shingles. There are 3, 4 or 5 bundles per square.

Butt edge: The lower edge of the shingle tabs.

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Caulk: To fill a joint with sealant, mastic or asphalt cement to prevent leaks.

Chalk line: A line made on the roof by snapping a taut string or cord dusted with chalk. Used for alignment purposes.

Class "A": The highest fire-resistance rating for roofing as per ASTM E-108. Indicates roofing is able to withstand severe exposure to fire originating from sources outside the building.

Class "B": Fire-resistance rating that indicates roofing materials are able to withstand moderate exposure to fire originating from sources outside the building.

Closed cut valley/ California Valley : A method of valley treatment in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed two inches from the valley centerline. The valley flashing is not exposed.

Closed soffit:   Underside of an overhang that is finished.

Coating: A layer of viscous asphalt, aluminum or emulsion applied to the outer roof surface to protect the roof membrane.

Color-through: During manufacturing, the color is mixed throughout the roofing material
to become an integral part of it. When the product is cut, the affected area shows the same color as the surface.

Concealed nail method: Application of roll roofing in which all nails are driven into the underlying course of roofing and covered by a cemented, overlapping course. Nails are not exposed to the weather.

Condensation: The change of water from vapor to liquid when warm, moisture-laden air comes in contact with a cold surface.

Chimney flashing: That portion of the flashing attached to a vertical surface to prevent water from migrating behind the base flashing.

Chimney counter flashing: L flashing installed at the base of the chimney to make the roof deck water tight.

Course: A row of shingles or roll roofing running the length of the roof.

Coverage: Amount of weather protection provided by the roofing material. Depends on number of layers of material between the exposed surface of the roofing and the deck; i.e., single coverage, double coverage, etc.

Cricket: A peaked saddle construction at the back of a chimney, skylight or wall to prevent accumulation of snow and ice and to deflect water around the chimney.

Cutout: The open portions of a strip shingle between the tabs.

Deck or Decking: The structural "skin" of a roof over which roofing in felt paper or base sheet is applied. Most new homes have decking made of plywood. There are four main types of decking commonly used on residential roofing projects:

•  Plywood: Plywood is strong, durable, and light. It comes in many grades with ratings from A to D. Use only exterior grade plywood for decking. The thickness of plywood depends on the spacing of the rafters.

•  OSB: Oriented strand board (OSB) is cheaper than plywood, but not as strong as plywood, and does not hold nails as well as plywood. One side has a slip resistant coating and should be placed facing up.

•  Tongue and groove 2x6: If a roof will be seen from the inside (no ceiling installed), tongue and groove is used. It is a wood decking that provides great insulation with the use of rigid roof insulation in moderate climates. Also, the boards can be painted or stained on the inside to match the interior.

Dormer: A framed small roof that projects through the sloping plane of a roof.

Double coverage : Application of asphalt roofing such that the lapped portion is at least two inches wider than the exposed portion, resulting in two layers of roofing material over the deck.

Downspout: A pipe for draining water from roof gutters.

Drip edge: A non-corrosive, non-staining material used along the gable, rakes or edges to allow water run-off to drip clear of underlying construction.

Eaves: Outside overhang of a flat or pitched roof.

Edging strips: 4x36 roofing shingles nailed along eaves and rakes to provide secure edges for re-roofing with asphalt shingles.

Exposure: Portion of the shingle exposed to the weather. Exposure is measured from the butt of one shingle to the butt of the next.

Feathering strips: Tapered wood filler strips placed along the butts of old roofing or sheeting to create a level surface when re-roofing over existing wood shingle roofs. Feathering strips are also called horse feathers.

Felt: Tar paper or felt paper. Available in 15 or 30 lbs. A flexible sheet that is saturated with asphalt and used as an underlayment.

Fiberglass mat: An asphalt roofing base material manufactured from glass fibers.

Flashing: Pieces of metal, rubber, lead or plastic used to prevent seepage of water into a building around any intersection or projection in a roof such as vent pipes, skylights, chimneys, adjoining walls, dormers and valleys. Galvanized metal flashing should be minimum 26 or 28-gauge. There are 4 main types of flashing used in residential roofing systems:

•  Valley flashing: This flashing is used in open valleys of the roof. Most often leaks are found in the valley flashings due to flashing that is nailed that is not trimmed far enough from the valley.

•  Plumbing vent flashing: Plumbing vent flashing prevents rainwater from running into holes cut for pipes penetrating through the roof. This flashing is sold according to the size of the vent pipe and the roof angle. Roof flashing is installed over the roofing and under the roofing above it.

•  Lead flashing: When working with tile roofs, lead flashing is used. In the case of a plumbing vent flashing, the lead flashing is actually molded to the shape of the tile's surface. Then the top of the lead flashing is covered by the next tile to prevent water from seeping under the flashing.

•  Step flashing: When a chimney or dormer wall intercepts the slope of the roof, step flashing is used. Step flashing is usually a metal piece that is bent in the middle, so that one end lays on the roof, and the other against the vertical wall of the dormer or chimney.

Flashing is one of the most important elements of the roof because it seals the seams and joints of the roof--the locations where leaks are most likely to occur. Often, flashing is not maintained well, or installed correctly in the first place. Check for the following signs that your flashing needs maintenance or repair:

•  Rusting of metal flashing

•  Excess leaves and debris in valleys or metal flashings of the roof (can lead to rusting and corroding of the metal)

•  Prolonged exposure to the elements such as moisture, UV rays, climate changes--especially when asphalt compounds or caulking material is used. Look for cracks, loss of elasticity and delamination.

In many cases the flashing can be cleaned and then repaired, relaminated or repainted (even in the case of rust). In other cases, the flashing may need to be replaced.

Flashing cement: An asphalt-based cement used to bond roofing materials. Flashing cement is also known as mastic.

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Gable roof: A type of roof containing sloping planes of the same pitch on each side of the ridge. A gable roof typically contains a gable at each end.

Gambrel roof: A type of roof containing two sloping planes of different pitch on each side of the ridge. The lower plane has a steeper slope than the upper. A gambrel roof usually contains a gable at each end, just like a standard gable roof.

Granules: Ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.

Gutter: The trough that channels water from the eaves to the downspouts.

Gutter Fascia: Horizontal trim at the eaves that covers the rafter ends.

Gutter Hangers: Aluminum brackets used to hang gutters with no visible fastener.

Gutter Spike and Ferrell: A gutter installation method using exposed fasteners on the exterior of the gutter.

Gutter Starter Metal: A baked enamel metal that is installed along the gutter edge to prevent water from affecting the sheeting.

Gutter Wedges: Used to hang gutters vertically on a sloped fascia board.

Hip: The inclined external angle formed by the intersection of two sloping roof planes. The hip runs from the ridge to the eaves.

Hip roof: A type of roof containing sloping planes of the same pitch on each of four sides. A hip roof contains no gables.

Hip shingles: Shingles used to cover the inclined external angle formed by the intersection of two sloping roof planes.

Ice and Water Shield: A waterproof underlayment material designed to protect against water infiltration caused by wind-driven rain, ice dams or low-pitched roof applications.

Ice dam: Ice dams occur when snow melts near the ridgelines of warm roofs (roofs without adequate ventilation). As the water runs down the roof to the overhang, it cools and freezes. If the snow continues this melt and freeze process, an ice dam can form that can seep under the shingles, through the decking and into the house. This, of course, can cause serious roof leaks--even in freezing temperatures.

The best prevention to ice dams is a well-ventilated (cool) roof. Additional protection for your roof can be applied with an impermeable ice and water membrane. The membrane is installed on top of the decking, under the roofing material. Temporary prevention of ice dams can also be done through the use of electric cables along the eaves of the roof (where the dams usually form). However, new ice dams can form above the cables and still cause extensive damage. Ice dams are very rare in the Northwest.

Intake Ventilation: The part of a ventilation system used to draw fresh air in. Usually vents installed in the soffit or along the eaves of a building.

Interlocking shingles: Individual shingles that mechanically fasten to each other to provide wind resistance.

Mansard roof: A type of roof containing two sloping planes of different pitch on each of four sides. The lower plane has a much steeper pitch than the upper, often approaching vertical. Contains no gables.

Re-cover (overlay): The installation of a new roof system over an existing system without removing an existing system.

Re-roofing: Installing a new roof system on a building that is not new.

Ridge: The uppermost, horizontal external angle formed by the intersection of two sloping roof planes.

Ridge Venting: A vent system used along the horizontal top of a roof for much better air space ventilation which is rated approximately 14 sq. inches per foot.

Rigid insulation:   Dense insulation boards nailed over a roof deck that is the finished ceiling.

Roll roofing: Asphalt roofing products manufactured in roll form which are not approved for residential use.

Roof scaffolding:  Brackets used on steeper roofs that hold 2x6 boards to prevent sliding.

Shed roof: A roof containing only one sloping plane. Has no hips, ridges or valleys.

Sheeting 1x8:   boards used to make solid roof deck, usually used prior to the use of plywood (prior to 1960).

Slope: The degree of roof incline expressed as the ratio of the rise, in inches, to the run, in feet.

Smooth-surfaced roofing: Roll roofing that is covered with ground talc or mica instead of granules (coated). It's recommended to coat these roofs with aluminum roof coating.

Steep slope application: Method of installing asphalt shingles on roof slopes greater than 21 inches per foot.

Step flashing: Flashing application method used where a vertical surface meets a sloping roof plane.

Storm Collar: Pre-formed flange placed over a vent pipe to seal the roof around the vent pipe opening. The collar is also called a vent sleeve.

Strip shingles: Asphalt shingles that are approximately three times as long as they are wide.

Turbines: A mechanical vent that spins and vents approximately 300 sq. ft. of attic space.

Valley:   The “V” created where two sloping roof planes meet each other.